This invention relates to automotive steer-by-wire systems, and more particularly, to such steer-by-wire systems with built-in redundancy.
Conventional automotive steering systems typically utilize hydraulic or electric systems to effect steering of a set of road wheels. However, vehicle design is constrained by such conventional steering systems because of the need to mount a rack and pinion gear laterally within the vehicle near the engine and transmission. Also constraining vehicle design is the need to connect the steering column in the passenger compartment to the steering gear on the underside of the vehicle. This is typically accomplished with an intermediate shaft and universal joints. The distances, alignment and angles between these components are critical and limit the placement of these components. Automotive steer-by-wire systems eliminate the mechanical connections between the steering wheel and the road wheels. However, typically the requirements of the steer-by-wire system as a whole, as well as that of the subsystems thereof, are more demanding than in conventional steering systems. In the event that one part of the steer-by-wire system becomes inoperative, it is desirable that redundancy is part of the steer-by-wire system so that continued operation of the vehicle may still be had.
An automotive steer-by-wire system is disclosed that includes a first network. The first network connects a first set of controllers for controlling a first set of motors. The steer-by-wire system further includes a second network that is independent of the first network and connects a second set of controllers for controlling a second set of motors. The steer-by-wire system includes a third network that connects the first set of controllers and the second set of controllers for controlling the first or second set of motors if the first or second network is inoperative, whereby information is transmitted via the third network independent of the first network and the second network.